Fertilising guide
How to fertilise Crimson Cestrum (Cestrum elegans)— schedule & NPK
Also called Crimson Cestrum, Purple Cestrum, Elegant Jessamine.
More about crimson cestrum
About Crimson Cestrum
Cestrum elegans · also called Crimson Cestrum, Purple Cestrum · tropical
Crimson Cestrum is a vigorous, arching evergreen shrub prized for its drooping clusters of deep crimson to purple-red tubular flowers produced from summer through autumn, followed by dark red berries. It thrives in full sun to partial shade in sheltered, well-draining soil. All parts are toxic. RHS hardiness H3 — suitable for mild UK gardens or cool glasshouses.
Growth habit: Upright to arching, vigorous evergreen shrub; can be wall-trained
What fertiliser crimson cestrum actually wants — and why
Crimson Cestrum is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for crimson cestrum: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed crimson cestrum, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For crimson cestrum:
Feed with a balanced liquid fertiliser every 3–4 weeks from spring through early autumn. Apply a slow-release fertiliser at the start of the growing season in containers. Tip prune young plants after feeding to encourage bushy growth and more flowering stems. Cease feeding in winter. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when crimson cestrum is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for crimson cestrum
Half strength is the safe default for crimson cestrum — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water crimson cestrum first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the crimson cestrum watering schedule.
Signs you are over-feeding crimson cestrum
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for crimson cestrum:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding crimson cestrum
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full crimson cestrum care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of crimson cestrum with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for crimson cestrum
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising crimson cestrum — frequently asked questions
What fertiliser does crimson cestrum need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Crimson Cestrum is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed crimson cestrum?
Feed with a balanced liquid fertiliser every 3–4 weeks from spring through early autumn. Apply a slow-release fertiliser at the start of the growing season in containers. Tip prune young plants after feeding to encourage bushy growth and more flowering stems. Cease feeding in winter. Feed with a balanced liquid fertiliser every 3–4 weeks from spring through early autumn. Apply a slow-release fertiliser at the start of the growing season in containers. Tip prune young plants after feeding to encourage bushy growth and more flowering stems. Cease feeding in winter. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for crimson cestrum?
Half strength is the safe default for crimson cestrum — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding crimson cestrum look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding crimson cestrum year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of crimson cestrum?
Flush the pot of crimson cestrum with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Crimson Cestrum care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water crimson cestrum — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise free-flowering cymbidium
- How to fertilise hooded maxillaria
- How to fertilise large-flowered maxillaria
- All 6887 fertilising guides in the Growli library